body {
    font-family: Arial, sans-serif;
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    line-height: 1.6;
    background-color: #f9f9f9;
}

.main-nav {
    display: flex;
    background-color: #0066cc;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 20px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.nav-link {
    display: block;
    padding: 12px 20px;
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: background-color 0.2s;
    flex: 1;
    text-align: center;
}

.nav-link:hover {
    background-color: #0052a3;
}

.nav-link.active {
    background-color: #004080;
    font-weight: bold;
}

.nav-back {
    margin-bottom: 20px;
}

.nav-back a {
    color: #0066cc;
    text-decoration: none;
    font-weight: bold;
}

.nav-back a:hover {
    text-decoration: underline;
}

.container {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    padding: 20px;
}

.nav-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin: 30px 0;
}

.nav-card {
    display: block;
    padding: 20px;
    background-color: #f8f9fa;
    border: 1px solid #e9ecef;
    border-radius: 8px;
    text-decoration: none;
    color: #333;
    transition: all 0.2s ease;
}

.nav-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.1);
    background-color: #e9ecef;
}

.nav-card h2 {
    margin-top: 0;
    color: #0066cc;
}

.nav-card p {
    margin-bottom: 0;
    color: #666;
}

.content {
    padding: 20px;
}

nav {
    background-color: #f0f0f0;
    padding: 15px 20px;
    display: flex;
    gap: 10px;
}

nav button {
    padding: 8px 16px;
    border: none;
    border-radius: 4px;
    background-color: #0066cc;
    color: white;
    cursor: pointer;
    transition: background-color 0.2s;
}

nav button:hover {
    background-color: #0052a3;
}

nav button.active {
    background-color: #004080;
}

h1 {
    color: #333;
    margin-bottom: 15px;
}

h2 {
    color: #444;
    margin-top: 20px;
    margin-bottom: 10px;
}

h3 {
    color: #555;
    margin-top: 15px;
    margin-bottom: 8px;
}

input, button {
    padding: 8px;
    margin: 5px;
    border-radius: 4px;
    border: 1px solid #ddd;
}

button {
    background-color: #4CAF50;
    color: white;
    cursor: pointer;
    transition: background-color 0.2s;
}

button:hover {
    background-color: #45a049;
}

.delete-btn {
    background-color: #f44336;
}

.delete-btn:hover {
    background-color: #d32f2f;
}

.tab-content {
    margin-top: 20px;
    padding: 15px;
    background-color: #f9f9f9;
    border-radius: 8px;
}

.display-area {
    margin-top: 15px;
    padding: 10px;
    background-color: #e9e9e9;
    border-radius: 4px;
}

.instructions {
    margin-top: 20px;
    padding: 15px;
    background-color: #f0f7ff;
    border-left: 4px solid #0066cc;
    border-radius: 4px;
}

.instructions code {
    background-color: #f0f0f0;
    padding: 2px 4px;
    border-radius: 3px;
    font-family: monospace;
}

.counter-container {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-top: 15px;
}

.counter-container span {
    font-size: 18px;
    font-weight: bold;
    min-width: 30px;
    text-align: center;
}

.list {
    margin-top: 15px;
    padding: 0;
    list-style-type: none;
}

.list li {
    display: flex;
    align-items: center;
    margin-bottom: 8px;
    gap: 10px;
}

.list li input {
    flex: 1;
}

.advantages {
    margin-top: 30px;
    padding: 15px;
    background-color: #f0f9f0;
    border-left: 4px solid #4CAF50;
    border-radius: 4px;
}

.advantages ul {
    margin-top: 10px;
    padding-left: 20px;
}

.advantages li {
    margin-bottom: 5px;
}

.examples {
    margin-top: 30px;
    padding: 15px;
    background-color: #f0f9ff;
    border-left: 4px solid #0066cc;
    border-radius: 4px;
}

.examples ul {
    margin-top: 10px;
    padding-left: 20px;
}

.examples li {
    margin-bottom: 10px;
}

.examples code {
    background-color: #f0f0f0;
    padding: 2px 6px;
    border-radius: 3px;
    font-family: monospace;
    color: #d63384;
}